Linear quantum-confined Stark effect and field tunable excitonic oscillator strength in bilayer WS<sub>2</sub>
ORAL
Abstract
The reflection symmetry is broken while the inversion symmetry is restored in bilayer TMDs unlike monolayers1. This results in anomalous field-dependent excitonic behavior in bilayer WS2 compared with monolayers. First, we show a linear quantum-confined Stark effect of bilayer intra-layer excitons with a vertical electric field, contrary to a quadratic one for a monolayer. Second, we demonstrate a strong field-dependent tunability of the oscillator strength of the intra-layer exciton due to a partial interconversion from intra-layer to inter-layer character with an increase in the vertical field. Third, using a modified device structure, we also show an efficient modulation of the excitonic response by transferring the oscillator strength from exciton to trion via electrostatic doping. These demonstrations make bilayer WS2 as an excellent candidate for the field tunable ultrathin electro-optical absorption modulator2 at the exciton resonance. These observations can find applications in various domains ranging from novel photonic devices, optical modulators, optical computing to imaging, and on-chip reconfigurable compact devices for next-generation optoelectronics.
References:
1. Das, S., et al. Phys. Rev. B 2019, 99, 165411.
2. Scuri, G., et al. Phys. Rev. Lett. 2018, 120, 037402.
References:
1. Das, S., et al. Phys. Rev. B 2019, 99, 165411.
2. Scuri, G., et al. Phys. Rev. Lett. 2018, 120, 037402.
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Presenters
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Sarthak Das
- Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore 560012, India
- Electrical communication engineering, Indian Institute of science
- Electrical Communication Engineering, Indian Institute of Science Bangalore